Sydney, Liverpool and Terrey Hills could experience between 80 and 100mm of rain on Tuesday while Campbelltown will see between 60 and 120mm. Newcastle could get 25 to 40mm of rain and the Blue Mountains National Park could get between 80 and 120mm.

In the past 24 hours, the SES has received more than 1290 calls for help and performed 25 flood rescues. There are 40 evacuation warnings still in place, with about 35,000 people still out of their homes.

Sydney’s Berkshire Park resident Cassie Gill has been pumping water from under her house for five days and said she’s never seen flooding this bad before.

“Every time we get a downpour it gets worse and worse, but after this next one we should be OK,” she said. “There’s too much water for it to go into the ground.”

While Ms Gill’s house has escaped the worst of the flooding, the family’s downstairs office has been flooded. “There is nowhere for the water to go,” she said.

By the time the clouds are predicted to lift at the end of this week, Sydney will have experienced ongoing rainfor more than a fortnight.

Meanwhile, additional defence force personnel will be sent to the Northern Rivers region to assist with the clean-up effort, with the SES trying to resupply communities with food and water.

More than 2000 homes and businesses in the state’s inundated Northern Rivers have been declared unliveable and NSW Premier Dominic Perrottet warned the recovery will take years as the true extent of the disaster becomes clear.

Two out of three flood-affected homes in Lismore, which bore the brunt of last week’s historic weather event, will need to be demolished and rebuilt, or substantially repaired, before they can be inhabited, while more than 200 schools across the state remain non-operational.

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While the NSW government has offered payments to those affected by floods, Lismore resident Tony Bazzana, whose accounting firm in town has been inundated by floodwaters, said it is not enough to help the community rebuild. Instead, he believes the government needs to increase incentives for people to stay in the region, such as by subsidising flood insurance.

“It’s hard to describe: it’s catastrophic. It’s just like nothing we’ve ever seen,” he said. “It’s like a war zone — there are no words to describe the community spirit but what we are facing is like nothing we have ever seen and the community can only do so much.”

Insurers are bracing for the biggest flood claim event in history. Insurance Council of Australia on Friday reported that 67,537 claims had been lodged so far, with the number continuing to rise.

Prime Minister Scott Morrison said the scale of this year’s floods had not been seen “in living memory in anyone’s lifetime.”

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“There is an enormous effort that is being put in to get to everywhere that people can get to,” he told 2GB on Monday morning. “But the real focus of the effort is up there in and around Lismore, which has had an experience that no one there has ever even heard of before in old stories, let alone in their own lived experience.

He added while he was aware that some communities remained cut off and stranded, work was being done to reach them.

“There’s food drops and helicopter assistance going into Evans Head over the next 24 hours. That should be happening very, very soon. The task is almost unimaginable for a flood we’ve ever seen in that part of Australia,” Mr Morrison said.

The biggest climate driver of the wet summer has been a La Nina event which has brought above-average rainfall, marine heatwaves and humid nights.

The Bureau of Meteorology’s Autumn Climate Outlook for 2022 suggests that, as La Nina wanes, Australia still faces a potentially wetter than average autumn, with night-time temperatures in many areas predicted to be higher than normal.

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